code: def get_pck3d(joints_3d_pre, joints_3d_gt):
      # about half of the head size
      threshold = 150 / 2048
      n, c, _ = joints_3d_pre.shape
      cnt = (
          np.linalg.norm(joints_3d_pre - joints_3d_gt, axis=-1)
          < threshold
      ).sum()
      return cnt / (n * c)
  
imports: import os
  import torch
  import torch.optim
  import numpy
  from sklearn.metrics import auc
label_desc: Use image node_id 20 for calling a global function with example usage: get_pck3d(joints_3d_pre, joints_3d_gt) and returns: unknown